Numerous types of attaching devices have been devised for securing support posts or other upstanding members in a selected position relative to a floor surface. Particularly in the case of handrail assemblies, the support posts or newels must be firmly anchored into the floor to withstand lateral forces which are imparted when a person leans on the handrail or grasps the handrail in ascending or descending a stairway. Attempts have been made to firmly anchor the newel by pigtailing directly through the newel into the floor. Also, corner brackets have been devised in which oppositely directed flanges at the lower end of the bracket alternately extend away from the lower edge of the bracket and are attached directly into the floor surface and, for example, reference is made to U.S. Letters Pat. No. 4,381,160 to Grimm et al. Brackets of this type are primarily intended for use in the original installation of the newels since the brackets must first be anchored in place to the floor surface and then attached to the base or lower end of the newel. However, it is desirable to provide for an anchor bracket assembly which is conformable for use either in the original installation of a newel or can be utilized to reinforce or repair existing newels and in such a way that any decorative trim or molding sections may be repositioned or placed over the bracket assembly once in position.